4-(Methylthio)butane-1,2-diol is an important compound as an intermediate of pharmaceuticals and a methionine analog (e.g. EP 338735 B and J. Agric. Food Chem., 23, 1137 (1975)). As the method for producing 4-(methylthio)butane-1,2-diol, a method comprising reacting 3-butene-1,2-diol with methanethiol in the presence of tert-butyl perphthalate and a method comprising reacting 3-butene-1,2-diol with methanethiol in the presence of a boron compound are described in J. Agric. Food Chem., 23, 1137 (1975) and EP 1260500 A, respectively.